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Abstract

Abstract:The first layers of rock underground are in thermal contact with the external atmosphere mainly through infiltrating meteoric water. This relatively cool zone absorbs rising geothermal energy, which heats the water. If the aquifer consists of gypsum, halite or quartzite, the water at those depths is usually salt-saturated, so the increase in temperature renders the water aggressive again. This in turn leads to rock dissolution and formation of phreatic conduits. This way, the geothermal flow creates caves that do not necessarily reach the surface. This paper analyzes the speed of the excavation, which, in different types of rocks, depends only slightly on temperature and meteoric precipitation. The time scale of this speleogenesis appears to be similar to that of other known cave systems. These processes are probably able to greatly increase the permeability around underground radioactive waste storage in halite.geothermal flux, phreatic speleogenesis, hypogenic caves, evaporite, quartzite, radioactive waste storage